I think it's still based on the A340. There is a company out there that sells built A340's that will hold 600-700 hp for $1799. A lot of supra guys use these trannies with good success. They also make trannies for LS/GS/SC 400/430 as well.
The place is called STC Inc. 847-640-7305
I just got a first-gen Toyota Sequoia at an excellent price. Will try to be somewhat of a resource on the forums for that from now on. Transmission and 4.7 V8 seem like they're barely broken in at 133,000 miles.